<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>el:挂载点</title>
</head>
<body>
{{ message }}
<h2 id="app" class="app">
    {{ message }}
    <span>{{ message }}</span>
</h2>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script>
    var app = new Vue({
        // el:"#app",
        // el:".app",
        // el:"div",
        el:"#body",
        data:{
            message:"黑马程序员"
        }
    })
</script>
</body>
</html>